In the article “The Relationship between Intragenerational and Intergenerational Ecological Justice” Glotzbach and Baumgärter identify the three logically possible hypotheses concerning the relationship between intragenerational and intergenerational ecological justice: independency, facilitation and rivalry. In addition to that, the authors successfully reveal the arguments in favour of each hypothesis and their underlying assumptions and interpretations. The authors do not make any claims about which of the three hypotheses is more plausible. But as the rivalry hypothesis is the most alarming — here the intra- and intergenerational needs are seen as incompatible — I assume the truth of this hypothesis in order to examine the tension that appears to come down to a trade-off between (1) preserving ecosystems and (2) extending the poor’s rights to use ecosystems. The core idea of the rivalry hypothesis is rather intuitive. It is argued that creating protected areas entails closing land use options for poor rural communities, whereas meeting the needs of today’s poor will be of the expense of long-term ecological interests. Basically, this hypothesis states that the quality and quality of existing ecosystem services are insufficient to fulfil both the justified claims of present and future people. However, Glotzbach and Baumgärtner convincingly show, it is useful to critically go through six determinants and reveal some of the underlying assumptions. In what follows I draw heavily on their paper. The first determinant concerns the quantity and quality of ecosystem services. Advocates of the rivalry hypothesis assume that ecosystem services are rivalry in consumption. Whereas certain provisioning services (e.g. related to food, fibre, freshwater) are, the use of many regulating services (e.g. climate regulation, air quality maintenance, erosion control), and cultural services (e.g. recreation, aesthetic experiences) does not diminish another’s ability to use the same service. The rivalry hypothesis states that what the ecosystems provide us with is simply insufficient to alleviate poverty without further environmental degradation. To alleviate poverty, they would say, is to expand the world economy and consequently intensify the problems of overuse. Ultimately the quality and quantity of delivering stocks, and supporting and regulating services are a given. This means that extending the poor’s rights to use ecosystems might require reducing them elsewhere (e.g. this would imply a loss of welfare for rich people, those people already with a good access). In order to make institutional arrangements about the use of ecosystem services, it is crucial to recognise their characteristics (determine which ones are rivalry/non-rivalry in consumption and which are excludable/non-excludable from use). However, advocates of the rivalry hypothesis do not consider such redistributions at all. To fight the rivalry hypothesis is to proof (1) that we can still restore degraded ecosystems or find substitutes, or (2) that political institutions could organise rights to use ecosystems. The second determinant is population development. Advocates of the rivalry hypothesis argue that population cannot be controlled at a stable number. There is disagreement about whether overpopulation causes the biggest threat to the Earth. It is argued that it is not the number of people on the planet, but rather the scale and nature of their consumption that is problematic. Whether it is overpopulation or overconsumption that really counts, increased levels of wellbeing and security seems to lessen “people’s desires to have more children than they and national ecosystems can support” Efforts to educate people about the impact of their choices and lifestyles would serve either case. Substitutability of ecosystem services by human-made goods and services forms a third determinant. The assumptions of advocates of the rivalry hypothesis with regard to the quality and quality of ecosystem services already indicate that they assume limited possibilities of substitutability. For any techno-optimist it is also important to consider the distinction Claassen makes between “factual substitutability” (in case two goods can fulfil the same functions) and the normative questions related to substitutability (do we want to substitute one function for the other). Following the capability theory of justice, Claassen argues that we are allowed to develop and replace resources as long as we can fulfil the same functions. However, this requires we have answers to the question which functions we think are normatively required. The fourth determinant is about technological progress. Advocates of the rivalry hypothesis doubt that technological progress can decouple total ecosystem pressure from economic growth. An increase in ecological efficiency, technological leapfrogging, could create more efficiency, but this might ultimately also increase the demand and ultimately raise the total consumption. I described this worry before in section I with the example of the LED-lights. Besides, it is important to clarify what we mean by eradicating poverty; is the resource consumption level of today’s industrialised countries to be taken as the standard? The fifth determinant is about all mechanisms which structure and govern human use of ecosystem services at all levels of society (institutions). And the sixth determinant relates to this as it concerns political restrictions. Advocates of the rivalry hypothesis are sceptical about the possibility to fundamentally alter political institutions from the local to the global level. They think political restrictions are tight. However, are those political power structures reason enough to not strive for change?